Originally Posted by
Retro Grouch
I wouldn't think that a pump head that screws onto a schrader valve would be a very good idea. Schrader heads have a little finger that depresses the poppet valve. During the time that it takes to unscrew the pump head you're going to lose a lot of the air that you just worked so hard to pump into your tire.
+1
I've used a Silca pump with a screw-on Schrader head, pumped up to 125psi (I know, I should be using Presta but it was the only spare tube I had), and watched as it let out 50psi worth of air as I unscrewed the head.